CAPTURING IMAGES USING SUB-FRAME ILLUMINATION

• US 20200137301A1
• Filed: 10/26/2018
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: Alibaba Group Holding Ltd.
• Original Assignee: Alibaba Group Holding Ltd.
• Inventors: Fields, Zikomo, Joshi, Yash
• Granted Patent: US 10,728,447 B2
• Time in Patent Office: Days
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 10/22 by selection of a specific region containing or referencing a pattern; Locating or processing of specific regions to guide the detection or recognition
• CPC Class Codes: G06V 40/166 using acquisition arrangements
• CPC Class Codes: G06V 40/19 Sensors therefor
• CPC Class Codes: G06V 40/193 Preprocessing; Feature extraction
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/611 where the recognised objects include parts of the human body
• CPC Class Codes: H04N 23/689 Motion occurring during a rolling shutter mode
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof
• CPC Class Codes: H04N 25/531 by controlling rolling shutters in CMOS SSIS

Abstract

The technology described in this document can be embodied in a method for capturing an image. The method includes generating a first control signal configured to cause a rolling shutter camera to capture an image of a subject over a first time period. The method also includes generating, at a first time point during the first time period, a second control signal configured to set a multi-spectral illumination source at a first intensity level. The multi-spectral illumination source is configured to illuminate the subject. The method further includes generating, at a second time point during the first time period, a third control signal configured to set the multi-spectral illumination source at a second intensity level that is less than the first intensity level. A portion of the image captured by the rolling shutter camera between the first and second time points includes a target feature associated with the subject.

Claims

1. A method for capturing an image, the method comprising:

generating a first control signal configured to cause a rolling shutter camera to capture an image of a subject, wherein the image is captured over a first time period;

generating, at a first time point during the first time period, a second control signal configured to set a multi-spectral illumination source at a first intensity level, wherein the multi-spectral illumination source is configured to illuminate the subject; and

generating, at a second time point during the first time period, a third control signal configured to set the multi-spectral illumination source at a second intensity level that is less than the first intensity level, wherein a portion of the image captured by the rolling shutter camera between the first and second time points includes a target feature associated with the subject.

2. The method of claim 1, wherein the target feature comprises an eye region of the subject.

3. The method of claim 2, wherein the target feature associated with the subject comprises eyes of the subject.

4. The method of claim 1, further comprising, prior to generating the first control signal, receiving, from a first image sensor, a first image of the subject captured without the multi-spectral illumination source being set to the first intensity level.

5. The method of claim 4, further comprising determining, based on the first image, a position of the target feature associated with the subject.

6. The method of claim 4, wherein the first image sensor is disposed in a first camera, and wherein the first image is captured using a higher camera gain than a camera gain used by the rolling shutter camera to capture the image.

7. The method of claim 1, wherein setting the multi-spectral illumination source at a second intensity level comprises turning off the multi-spectral illumination source.

8. The method of claim 1, wherein a difference between the first time point and the second time point is less than about 10 milliseconds.

9. The method of claim 1, wherein the multi-spectral illumination source comprises a light-emitting diode (LED) element.

10. A system comprising:

a rolling shutter camera;

a multi-spectral illumination source; and

one or more processing devices in communication with the rolling shutter camera and the multi-spectral illumination source, the one or more processing devices configured to;

generate a first control signal configured to cause the rolling shutter camera to capture an image of a subject, wherein the image is captured over a first time period;

generate, at a first time point during the first time period, a second control signal configured to set the multi-spectral illumination source at a first intensity level, wherein the multi-spectral illumination source is configured to illuminate the subject; and

generate, at a second time point during the first time period, a third control signal configured to set the multi-spectral illumination source at a second intensity level that is less than the first intensity level, wherein a portion of the image captured by the rolling shutter camera between the first and second time points includes a target feature associated with the subject.

11. The system of claim 10, wherein the target feature associated with the subject comprises an eye region of the subject.

12. The system of claim 11, wherein the target feature associated with the subject comprises eyes of the subject.

13. The system of claim 10, wherein the one or more processing devices are configured to receive from a first image sensor, prior to generating the first control signal, a first image of the subject captured without the multi-spectral illumination source being set to the first intensity level.

14. The system of claim 13, wherein the one or more processing devices are configured to determine, based on the first image, a position of the target feature associated with the subject.

15. The system of claim 13, wherein the first image sensor is disposed in a first camera different from the rolling shutter camera, and wherein the first image is captured using a higher camera gain than a camera gain used by the rolling shutter camera to capture the image.

16. The system of claim 10, wherein setting the multi-spectral illumination source at a second intensity level comprises turning off the multi-spectral illumination source.

17. The system of claim 10, wherein a difference between the first time point and the second time point is less than about 10 milliseconds.

18. The system of claim 10, wherein the multi-spectral illumination source comprises a light-emitting diode (LED) element.

19. One or more machine-readable storage devices comprising machine-readable instructions configured to cause one or more processing devices to perform operations comprising:

generating a first control signal configured to cause a rolling shutter camera to capture an image of a subject, wherein the image is captured over a first time period;

generating, at a first time point during the first time period, a second control signal configured to set a multi-spectral illumination source at a first intensity level, wherein the multi-spectral illumination source is configured to illuminate the subject; and

generating, at a second time point during the first time period, a third control signal configured to set the multi-spectral illumination source at a second intensity level that is less than the first intensity level, wherein a portion of the image captured by the rolling shutter camera between the first and second time points includes a target feature associated with the subject.

20. The one or more machine-readable storage devices of claim 19, wherein the target feature comprises an eye region of the subject.